The earth's rotation rate is slowing down because of friction against the tidal bulges caused by the gravitation of the moon (major factor) and the sun (lesser factor). The earth's rotational energy is dissipated as heat, but where is the angular momentum going, and what physical mechanism brings that momentum there?
(In reply to
re: I disagree - me too, with you by ThoughtProvoker)
Sorry I didn't respond before now, ThoughtProvoker, but...
I'm not confusing energy with angular momentum. Both are conserved. The question is, what's happening to them? Let's go back to the egg. Compare spinning a raw egg and a hard-boiled egg. Try it if you never have. The hard-boiled egg will spin like a top for 20-30 seconds. But you can't get the raw egg to spin more than 5 or 6 rotations. (This is a classic way to tell if an egg is hard-boiled.) Why is this?
I agree that angular momentum is conserved...so is energy, by the way... but where is it? I submit that it's being "dissipated" by lots of little currents set up in the internal fluid, slowing down the body (the egg) as a whole. The total angular momentum of all this motion is conserved, but the rate of rotation of the egg has obviously slowed way down. (Air resistance and friction against the table are very minor contributors--as the hard-boiled egg demonstrates.)
So, in the case of the earth, I contend that the slow-down is more due to the transfer of angular momentum (and energy!) to the fluids on the earth's surface in the form of hurricanes (and other atmospheric phenomena) and ocean currents, than it is due to the moon. I also believe that the rate of slow-down would be roughly the same, even if there were no moon.
I wonder if this could be settled by finding out if we have data about the rotation of Venus--a planet roughly the same size as the earth, but which has no moon. Unfortunately, I don't think we have accurate data on the rate of Venus' rotation, since it's so completely covered with clouds. But I'll do a search after I post this--if I find anything, I'll post it here.
re(2): I disagree - me too, with you
